Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Soukaina Akel
  • Ralf Dillert
  • Narmina O. Balayeva
  • Redouan Boughaled
  • Julian Koch
  • Mohammed El Azzouzi
  • Detlef Bahnemann Detlef Bahnemann

External Research Organisations

  • Mohammed V University in Rabat
  • Saint Petersburg State University
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Details

Original languageEnglish
Article number647
JournalCATALYSTS
Volume8
Issue number12
Early online date10 Dec 2018
Publication statusPublished - Dec 2018

Abstract

Mixtures and composites of Ag/Ag 2 O and TiO 2 (P25) with varying mass ratios of Ag/Ag 2 O were prepared, employing two methods. Mechanical mixtures (TM) were obtained by the sonication of a suspension containing TiO 2 and Ag/Ag 2 O. Composites (TC) were prepared by a precipitation method employing TiO 2 and AgNO 3 . Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag(0) and Ag 2 O. The activity of the materials was determined employing methylene blue (MB) as the probe compound. Bleaching of MB was observed in the presence of all materials. The bleaching rate was found to increase with increasing amounts of TiO 2 under UV/vis light. In contrast, the MB bleaching rate decreased with increasing TiO 2 content upon visible light illumination. XRD and XPS data indicate that Ag 2 O acts as an electron acceptor in the light-induced reaction of MB and is transformed by reduction of Ag + , yielding Ag(0). As a second light-induced reaction, the evolution of molecular hydrogen from aqueous methanol was investigated. Significant H 2 evolution rates were only determined in the presence of materials containing more than 50 mass% of TiO 2 . The experimental results suggest that Ag/Ag 2 O is not stable under the experimental conditions. Therefore, to address Ag/Ag 2 O as a (photo)catalytically active material does not seem appropriate.

Keywords

    Hydrogen evolution, In situ deposition, Mechanical mixture, Photocatalysis, Silver(II) oxide, Titanium dioxide

ASJC Scopus subject areas

Cite this

Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio. / Akel, Soukaina; Dillert, Ralf; Balayeva, Narmina O. et al.
In: CATALYSTS, Vol. 8, No. 12, 647, 12.2018.

Research output: Contribution to journalArticleResearchpeer review

Akel, S, Dillert, R, Balayeva, NO, Boughaled, R, Koch, J, Azzouzi, ME & Bahnemann, DBD 2018, 'Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio', CATALYSTS, vol. 8, no. 12, 647. https://doi.org/10.3390/catal8120647, https://doi.org/10.15488/4912
Akel, S., Dillert, R., Balayeva, N. O., Boughaled, R., Koch, J., Azzouzi, M. E., & Bahnemann, D. B. D. (2018). Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio. CATALYSTS, 8(12), Article 647. https://doi.org/10.3390/catal8120647, https://doi.org/10.15488/4912
Akel S, Dillert R, Balayeva NO, Boughaled R, Koch J, Azzouzi ME et al. Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio. CATALYSTS. 2018 Dec;8(12):647. Epub 2018 Dec 10. doi: 10.3390/catal8120647, 10.15488/4912
Akel, Soukaina ; Dillert, Ralf ; Balayeva, Narmina O. et al. / Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio. In: CATALYSTS. 2018 ; Vol. 8, No. 12.
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T1 - Ag/Ag2O as a Co-Catalyst in TiO2 Photocatalysis: Effect of the Co-Catalyst/Photocatalyst Mass Ratio

AU - Akel, Soukaina

AU - Dillert, Ralf

AU - Balayeva, Narmina O.

AU - Boughaled, Redouan

AU - Koch, Julian

AU - Azzouzi, Mohammed El

AU - Bahnemann, Detlef Bahnemann Detlef

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N2 - Mixtures and composites of Ag/Ag 2 O and TiO 2 (P25) with varying mass ratios of Ag/Ag 2 O were prepared, employing two methods. Mechanical mixtures (TM) were obtained by the sonication of a suspension containing TiO 2 and Ag/Ag 2 O. Composites (TC) were prepared by a precipitation method employing TiO 2 and AgNO 3 . Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ag(0) and Ag 2 O. The activity of the materials was determined employing methylene blue (MB) as the probe compound. Bleaching of MB was observed in the presence of all materials. The bleaching rate was found to increase with increasing amounts of TiO 2 under UV/vis light. In contrast, the MB bleaching rate decreased with increasing TiO 2 content upon visible light illumination. XRD and XPS data indicate that Ag 2 O acts as an electron acceptor in the light-induced reaction of MB and is transformed by reduction of Ag + , yielding Ag(0). As a second light-induced reaction, the evolution of molecular hydrogen from aqueous methanol was investigated. Significant H 2 evolution rates were only determined in the presence of materials containing more than 50 mass% of TiO 2 . The experimental results suggest that Ag/Ag 2 O is not stable under the experimental conditions. Therefore, to address Ag/Ag 2 O as a (photo)catalytically active material does not seem appropriate.

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